Fire crews responded this evening to the Mack Trucks Inc. plant in Lower Macungie Township for a truck on fire inside the facility, according to emergency radio broadcasts.

Security at the Macungie Cab and Vehicle Assembly plant, 7000 Alburtis Road, reported the fire about 6 p.m. The building was being evacuated.

As of about 6:10 p.m., responders reported heavy smoke from the western portion of the building but said it was believed the facility's sprinkler system had knocked down the fire, the broadcasts indicated.

Fire crews reportedly planned on entering the plant with a hose line.

The fire was reportedly under control by about 6:25 p.m. Crews planned to get the damaged truck outside and then ventilate the building.

On its website, Mack Trucks says its entire Mack product line is manufactured at this 1-million-square-foot plant outside Allentown.